1. Field of the Invention
The present invention relates to spectacle lenses and a pair of spectacles using the same.
A pair of spectacles using highly-curved lenses represented by the 8-base curve are effective for improving the field of view, minimizing the space between the spectacle frame and the face of the user and the entry of wind and light into the space between the spectacles and the face of the user.
2. Description of Prior Art
The conventional spectacle lenses of the above-described kind are generally formed in such a manner that the geometrical center of each of the lenses coincides with the optical center thereof.
However, as shown in FIG. 5, a pair of spectacles using highly-curved lenses extending along the face of the user have the disadvantage that since the lenses incline forward as they respectively extend along the face of the user from the outer ends toward the inner ends thereof in the horizontal direction, unless the optical center of each of the lenses is set at a position near the nose N of the user rather than at a position E of each of the pupils of the eyes of the user, the degree of parallelism becomes too large for the user to see the things well. Further, when such highly-curved lens is attempted to extend along the face of the user, the lens usually inclines forward by 10 through 15 degrees. In this case, the mere setting of the optical center of the lens on the side of the nose N of the user rather than on the side of the user""s pupil position E results in making the degree of parallelism in the vertical direction too large for the user to see things well.
The present invention has been made in view of the above-described problems and an object of the invention is to provide spectacle lenses and a pair of spectacles making use of such spectacle lenses each of which have a reduced degree of parallelism as one of the optical performances thereof, so that when the pair of spectacles are worn by a user with the lenses kept extending along the face of the user, the user can clearly see the things in front of him.
According to a technical means provided by the present invention for solving the above-described problems is that a pair of tabs are fixed to the outer periphery of each of main bodies of uncut spectacle lenses in opposite relationship with each other, each of the main bodies has an optical center (b) at a position spaced apart from the geometrical center (a) thereof and a line (c) which connects the geometrical center (a) and the optical center (b) makes a predetermined angle with respect to a central line (d) which passes through the pair of tabs and the geometrical center (a) of the lens body.
Accordingly, when each of the uncut spectacle lenses is cut to the shape of the spectacle frame corresponding thereto, the pair of tabs can be used to serve as a means (or a jig) for positioning the optical center (b) of each of the lenses at a predetermined position of the lens and by making use of such tabs, it is possible to cut each of the uncut spectacle lenses easily and accurately. Further, it is possible to manufacture a pair of spectacles by making use of such uncut spectacle lenses in such a manner that when the user wears the pair of spectacles, the optical center (b) of each of the spectacle lenses come to lie inside and above the geometrical center (a) thereof in the horizontal direction and further, when the user causes the spectacle lenses to extend along his face, the degree of parallelism as one of the optical performances of the lens can be made small thereby allowing the user to clearly see things in front of him.
Another technical means according to the present invention is that the connecting line (c) makes a predetermined angle, that is about 20 degrees, with respect to a central line (d).
Accordingly, when the pair of spectacles are worn by a user with the lenses kept extending along the face of the user, the degree of parallelism of the lenses in the vertical direction can be made as small as possible for the user to see the things in front of him further well.
According to another technical means provided by the present invention for solving the above-described problems is that in the case of a polarizing uncut spectacle lens, the lens has an optical center (b) at a position spaced apart from the geometrical center (a) of the lens, and the distance between the geometrical center (a) and a parallel line (e) drawn parallel to the axis of polarization from the optical center (b) of the lens is in the order of 8.21 mm xc2x15 mm.
Accordingly, when the user wears the pair of spectacles in such a manner that the spectacle lenses extend along the face of the user, the degree of parallelism of the lens in the vertical direction and that of the lens in the horizontal direction can be made as small as possible so that the user can see more clearly things in front of him.
A further technical means provided by the present invention is that the optical center (b) of the above-described lens lies at a position spaced apart from the geometrical center (a) of the lens by 19 mm through 29 mm.
Accordingly, when the user wears his pair of spectacles in such a manner that the spectacle lenses extend along his face, the degree of parallelism in the horizontal direction can be made as small as possible thereby allowing the user to see more clearly things in front of him.
A still further technical means provided by the present invention is that at least a pair of tabs are fixed to the outer periphery of the main body of each of the spectacle lenses in spaced relationship with each other so that when a plurality of such lenses are laid one above another, the tabs support the outer periphery of one of the adjoining lens thereby preventing the adjoining lenses from coming into contact with each other and preventing the surface of each of the lenses from getting scratched.
A still further technical means provided by the present invention is that the pair of tabs project from the outer periphery of the main body of each of the uncut spectacle lenses by 2 mm or more both in length and width.
Accordingly, when the pair of tabs are used as a means for positioning the optical center (b) of the lens at a predetermined position of the lens, the positioning operation can be performed more accurately at the time of cutting and it is possible to cut the uncut spectacle lens more simply and more accurately.
A still further technical means provided by the present invention is that that a line connecting the centers of at least a pair of tabs passes through the geometrical center (a) of the lens.
Accordingly, the pair of tabs can be effectively made use of as a means for positioning the optical center (b) at a predetermined position on the lens.
A still further technical means provided by the present invention is that the optical center (b) of each of the spectacle lens lies at a position spaced apart from the geometrical center (a) thereof so that when a user wears a pair of spectacles using such lenses, the optical center (b) of each of the lenses lies at a position displaced inward and upward from the geometrical center (a) of the lens in the horizontal direction.
Accordingly, when a pair of spectacles making use of such lenses is manufactured, it is possible to constitute each of the spectacle lenses in such a manner that the optical center (b) of the lens lies at a position displaced inward and upward from the geometrical center (a) thereof so that when a user wears the pair of spectacles along his face, the degree of parallelism of the lens which is one of the performances of the lens can be made small thereby allowing the user to clearly see things in front of him.
A still further technical means provided by the present invention is that in the case of a polarizing spectacle lens, the optical center (b) of the lens is at a position spaced apart from the geometrical center (a), and a line (c) connecting the optical center (b) and the geometrical center (a) makes a predetermined angle with respect to the axis of polarization of the lens.
Accordingly, when a user wears a pair of spectacles using such lenses, the axis of polarization of each of the spectacle lenses is directed toward the horizontal direction and also when the pair of spectacles are held extending along the face of the user, the degree of parallelism of the lens becomes favorable so that the user can clearly see things in front of him.
A still further technical means provided by the present invention is the above-described spectacle lens has a lens curve having six or more bases.
A still further technical means provided by the present invention resides with a pair of spectacles making use of the above-described spectacle lenses.